Cryo balloon

ABSTRACT

Devices and methods for performing cryo therapy, cryo ablation or cryoplasty. A cryo therapy apparatus may comprise an elongate shaft, a cooling member disposed at the distal end of the shaft, and a pressure gauge coupled to the cooling member.

1. FIELD OF THE INVENTION

[0001] The present invention pertains generally to the field of cryotherapy. More particularly, the present invention pertains to cryoablation catheters for use in causing cold-induced necrosis andcryoplasty catheters for use in causing apoptosis to prevent restenosis.

2. DESCRIPTION OF THE RELATED ART

[0002] A number of medical conditions may be treated using ablativetechniques or devices. Ablative techniques, generally, result indestroying the function of abnormal tissue at an area of interest.Destroying the function of the abnormal tissue may result in anefficacious treatment for a medical condition. For example, atrialfibrillation may be the result of abnormal electrical activity in theleft atrium and the pulmonary vein, and may be treatable by ablation ofthe abnormal tissue within the left atrium and/or the pulmonary vein.

[0003] Atrial fibrillation is a serious medical condition that is theresult of abnormal electrical activity within the heart. This abnormalactivity may occur at regions of the heart including the sino-atrial(SA) node, the atriovenricular (AV) node, the bundle of His, or withinother areas of cardiac tissue. Moreover, atrial fibrillation may becaused by abnormal activity within a isolated focal center within theheart. It is believed that these foci can originate within the pulmonaryvein, particularly the superior pulmonary veins.

[0004] Minimally invasive techniques have been described that useablation catheters to target the pulmonary vein with the hope ofablating foci having abnormal electrical activity. The techniquestypically are characterized by application of energy to cause lesionswithin the foci or other areas possessing abnormal electrical activity.

[0005] Some ablation devices utilize radio frequency (RF) energy forablation. The RF energy devices may be used to ablate an area ofinterest with heat. The use of RF energy for ablation may, however, leadto untoward healing responses such as collagen build up at the area ofinterest after treatment. Moreover, RF ablation of within an atrium maydecrease atrial output. A need, therefore, exists for ablative devicesand methods that include improved healing responses.

[0006] An alternative treatment strategy has been developed that usescooling energy for ablation. This method, termed cryoplasty or cryotherapy, may be used to cool the lesion to freeze a portion of theaffected area. For example, cryoplasty may be used to freeze a lesionwithin a blood vessel to induce apoptosis or remodeling that mightotherwise lead to restenosis or recoil. In addition to its potentialutility in preventing and slowing restenosis and addressing recoil, cryotherapy may be used for ablation techniques. For example, cryo therapymay be efficacious in varicose vein treatment of incompetent valves,valvular disease, mitral valve regurgitation therapy, atrialfibrillation, gastric reflux disease, gastro esophageal reflux disease,GURD, esophageal disease, cancer treatment including stomach or uterinecancer, etc.

SUMMARY OF THE INVENTION

[0007] The present invention pertains to cryo therapy catheters. Moreparticularly, the present invention comprises a cryo therapy deviceincluding a pressure gauge to monitor the pressure within an inflatableportion of the cryo therapy apparatus and a pressure release tube thatmay comprise a conduit for coolant to escape should pressure become toogreat. The present invention can be used to ablate tissue (such asabnormal tissue within the pulmonary vein), ablate tissue in orderprevent restenosis in the vasculature and cardiac tissue, and ablateother target regions where cryo therapy may have beneficial effects.

[0008] The cryo therapy device may include an elongate shaft having acooling member disposed at the distal end thereof. The pressure gaugemay be coupled to the cooling member. The pressure gauge may comprise astrain gauge that may include a direct or indirect measure of pressurewithin the inner member that may be quantified directly or indirectly bya clinician. In an alternate embodiment, the pressure gauge may comprisea horizontal strain gauge. A horizontal strain gauge is substantiallysimilar to the strain gauge detailed above except that it may bedisposed at the inner member in a differing pattern. The pressure gaugemay also be an optical, piezoelectric, magnetic, or mechanical microsensors disposed within the cryo chamber.

[0009] The pressure release tube has a proximal end, a distal end, and alumen extending therethrough. A removable valve may be disposed at theproximal end of the pressure release tube. The removable valve may beremoved from the pressure release tube to allow pressure to escape fromthe inner member. In addition, a pressure-sensitive valve may bedisposed at the distal end of the pressure release tube. Thepressure-sensitive valve is understood to be a valve disposed at thedistal end that will provide an opening to the lumen of the pressurerelease tube if the pressure within the inner member becomes too great.The pressure relief valve may also be a pressure relief mechanism suchas a puncture device such as an RF relief cutter, or alternatively amechanical needle to puncture the balloon and create a controlledrelease of gas. The controlled release of gas may be into an isolationchamber surrounding the cryo chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 is a cross-section of a cryo therapy device having apressure gauge and a pressure release tube;

[0011]FIG. 2 is a partial cross-section of a cryo therapy device havinga fuse link coupled to the pressure relief tube;

[0012]FIG. 3 is a partial cross-section of a cryo therapy device havinga relief cutter coupled to the inner surface of the inner member of thecooling chamber; and

[0013]FIG. 4 is a cross-section of a cryo therapy device having analternate pressure gauge and a pressure release tube.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The following description should be read with reference to thedrawings wherein like reference numerals indicate like elementsthroughout the several views. The detailed description and drawingsrepresent select embodiments and are not intended to be limiting.

[0015]FIG. 1 is a cross-section of a cryo therapy device 10 having apressure gauge 12 and a pressure release tube 14. Pressure gauge 12 iscoupled to a cooling member 16, for example on an inner member 26.Pressure gauge 12 may be used to quantify pressure within cooling member16. Cooling member 16 is coupled to an elongate shaft 18. In addition,at least a portion of pressure relief tube 14 is disposed within coolingmember 16. Pressure relief tube 14 may be used to releaseinflation/cooling media from cooling member 16. This could be done, forexample, when the pressure in cooling member 16 as detected by gauge 12is in excess of a desired limit.

[0016] Cryo therapy device 10 may use heat transfer to perform a numberof procedures including pulmonary vein ablation, pulmonary arteryablation, atrial fibrillation, arrhythmia, and other conditions.Moreover, cryo therapy device 10 may be used to prevent restenosis inthe vasculature (including the pulmonary artery and vein), cardiactissue (including atria and ventricles), and other target regions wherecryoplasty may have beneficial effects.

[0017] Shaft 18 includes a proximal end 20 and a distal end 22. Shaft 18may be generally tubular and may be comprised of material including, butnot limited to, metals, stainless steel, nickel alloys, nickel-titaniumalloys, thermoplastics, high performance engineering resins, fluorinatedethylene propylene (FEP), polymer, polyethylene (PE), polypropylene(PP), polyvinylchloride (PVC), polyurethane, polytetrafluoroethylene(PTFE), polyether block amide (PEBA), polyether-ether ketone (PEEK),polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide(PPO), polysufone, nylon, perfluoro(propyl vinyl ether) (PFA), andcombinations thereof. In addition, a guidewire tube 19 having aguidewire lumen 21 extending therethrough (and through cooling member16) may be disposed within shaft 18.

[0018] Cooling member 16 may be disposed at a distal end 22 of shaft 18.Cooling member 16 may comprise an outer member 24, inner member 26, andan annular space 28 therebetween. As an alternate feature, a vacuumsource can be fluidly connected to device 10 to evacuate space 28. Bothouter member 24 and inner member 26 can be, for example, balloonscomprised of polyether block amide (PEBA). Outer member 24 and innermember 26 can have a burst pressure, for example, of about 6 to 24atmospheres. Polyether block amide is commercially available fromAtochem Polymers of Birdsboro, Pa., under the trade name PEBAX.Alternatively, cooling member 16 may be comprised of materials listedabove.

[0019] Inner member 26 is in fluid communication with a coolant source.For example, the coolant source may be coupled to inner member 26 by aninflation tube 30 and a drain tube 32 each disposed within shaft 18. Theinflation tube and the drain tube are substantially similar to analogousobjects disclosed within U.S. Pat. No. 5,868,735 to Lafontaine and U.S.patent application Ser. No. 09/849,892 to Lafontaine, the entiredisclosures of which are hereby incorporated by reference. Outer member24 may contain coolant which may escape from inner member 26. Cryotherapy device 10 may further comprise additional elements and featuresdisclosed within the above-incorporated references.

[0020] Proximal end 20 of elongate shaft 18 may be connected to amanifold 34. Manifold 34 may comprise a coolant source. For example,manifold 34 may comprise a coolant source coupled to inner member 26 viainflation tube 30. Additionally, manifold 34 may comprise means foractuating (i.e., inflating) inner member 26 adapted to connect to aninflation pump.

[0021] Inner member 26 may further comprise an inner surface 36 and anouter surface 38. Pressure gauge 12 may be disposed at outer surface 38.In an alternative embodiment, pressure gauge 12 may be disposed at innersurface 36. Pressure gauge 12 may be connectable to manifold 34 by aconnector 40.

[0022] Pressure gauge 12 may comprise, for example, a strain gauge, fuselink, optical transmitter with a fiber optic output, etc. In general,the length of pressure gauge 12 may be altered by increasing the sizeand/or pressure of inner member 26 (e.g., by inflation with a coolant).Therefore, the strain of pressure gauge 12 may comprise a direct orindirect measure of pressure within inner member 26. The fuse linkembodiment would measure pressure in a threshold manner. For example,when the balloon pressure expands the balloon to a size that breaks thelink, the interruption of conductivity would be sensed and indicateexcessive pressure. The optical transmitter with a fiber optic outputembodiment would allow a user to visualize inner member 26 to determineif pressure should be altered. For example, connector 40 may comprise afiber optic output and manifold 34 may include a optical transmitter. Ingeneral, optical visualization may be accomplished in any manner that isknown in the art.

[0023] Means for quantifying strain and/or stress may include an analogreading or display, a digital reading or display, a connector forcoupling to a computerized system for quantifying strain, a computerizedsystem for processing other data, and combinations thereof. A person ofordinary skill in the art would be familiar with these and alternativemeans for quantifying strain according to multiple embodiments of theinvention and converting the strain measurement to a pressuremeasurement.

[0024] Pressure release tube 14 may comprise a proximal end 42, a distalend 44, and a lumen 46 extending therethrough. Pressure release tube 14may be comprised of materials similar to those listed above. Pressurerelease tube 14 may comprise a conduit for a coolant to escape frominner member 26 if pressure therein exceeds a desired limit. Forexample, inner member 26 may comprise a burst pressure of 8 atmospheres.Pressure release tube 14 may be in fluid communication with inner member26. If the pressure within inner member 26 approaches the burstpressure, coolant may be removed from inner member 26 through pressurerelease tube 14.

[0025] A removable valve 48 may be disposed at proximal end 42 ofpressure release tube 14. According to this embodiment, if pressurewithin inner member 26 approaches a desired limit, for example, theburst pressure, removable valve 48 may be removed from pressure releasetube 14 to allow pressure to escape inner member 26. Removable valve 48may be located proximate manifold 34 so that it may be available to auser of cryo therapy device 10.

[0026] In use, pressure within inner member 26 may be measured bypressure gauge 12 and may be quantified. The amount of pressure withininner member 26 may be available to a clinician performing a medicalprocedure. If the pressure becomes too great within inner member 26 orapproaches the burst pressure thereof, the clinician may removeremovable valve 48 from pressure release tube 14. Removing removablevalve 48 from pressure release tube 14 will reduce pressure within innermember 16.

[0027] A pressure-sensitive valve 50 may be disposed at distal end 44 ofpressure relief tube 14. Pressure-sensitive valve 50 is understood to bea valve disposed at distal end 44 that will provide an opening to lumen46 if the pressure within inner member 26 becomes too great (e.g.,approaches a desired limit, such as the burst pressure of inner member26). Pressure-sensitive valve 50 may be used with or without removablevalve 48.

[0028]FIG. 2 is a partial cross-section of cryo therapy device 10 havinga fuse link 52 coupled to pressure relief tube 14. Fuse link 52 may beused independently or in conjunction with valve 48, cap 50, or both.Fuse link 52 includes a portion that covers a vent opening 54 withinpressure relief tube 14 and is coupled to pressure sensor (P) such thatwhen pressure exceeds a threshold level, current (I) is increased withinfuse link 52 sufficient to burn fuse link 52 and expose vent opening 54,which allows cooling chamber 16 to be vented. The pressure sensor maycomprise a number of objects such as strain gauge 12, a piezoelectricMEMS (microelectromechanical systems) sensors, a fiber optic sensor,optical sensors, walls of cooling chamber 16, magnetic or mechanicalmicro sensors disposed within cooling chamber 16, etc. It should benoted that FIG. 2 depicts the pressure gauge as being connected toconnector 40 of pressure gauge 12 at manifold 34. However, any of thepressure sensors listed above may be substituted and coupled to fuselink 52 at any convenient location such as at manifold 34, withincooling chamber 16, etc.

[0029] The pressure sensor and fuse link 52 may be coupled by anelectrical circuit. For example, the pressure signal may be amplifiedand then compared with a pressure threshold at a second amplifier. Thepressure threshold may be set a desired level near and/or less than theburst pressure of inner member 26. Pressure in excess of the burstpressure may be further amplified (for example, to correct or increasethe signal) an go on burn fuse link 52 and expose opening 54. It can beappreciated that other suitable configurations of electrical circuitsmay be substituted without departing from the spirit of the invention.

[0030]FIG. 3 is a partial cross-section of cryo therapy device 10 havinga relief cutter 56 coupled to inner surface 36 of inner member 26.Relief cutter 56 may be used independently or in conjunction with valve48, cap 50, fuse link 52, or combinations thereof. Relief cutter 56 maybe comprised of one or more wires 58 (e.g., about 0.007 inches indiameter, more, or less) disposed along inner surface 36 of inner member26. For example, relief cutter 56 may comprise two parallel insulatedwires installed on inner surface 36. The wires may be spaced a distance(e.g., 0.02 about inches, more, or less) and be connected to source ofpotential energy (V) such as a radio-frequency (RF) energy source, alaser energy source, an ultrasonic energy source, etc. Electrodes 60 maybe disposed on the ends of wires 58 for generating a spark or othercutting means. In an alternative embodiment, relief cutter 56 maycomprise a mechanical puncture device such as a needle, a pull wire, orother suitable object.

[0031] To actuate relief cutter 56, energy (RF) is applied to wires 58,which creates a spark or other suitable cutting means at electrodes 60.The spark can result in a relatively small hole (e.g., about 0.25 inchesin diameter, more, or less) within inner member 26. The hole allowscoolant contained within inner member 26 to be vented out into outermember 24 and out of the catheter through an outer lumen 62. Outer lumen62 is in fluid communication with manifold 34 so that any vented coolantmay be contained therein. For example, manifold 34 may includes anopening 64 for cooling to be vented through and into a holding vesselwithin manifold 34. It is believed that relief cutter 56 will createsmall holes within inner member 26 without causing further tearing ordissection of inner member 26.

[0032] Relief cutter 56, may be connected to a pressure gauge (e.g.,strain gauge 12 and others described above) via an electrical circuit.This may allow automated actuation of relief cutter 56 in the event ofpressure approaching the burst pressure of inner member 26. For example,the energy source may be switched on by an amplified signal from thepressure gauge (similar to how the pressure signal actuates fuse link52).

[0033]FIG. 4 is a cross-section of cryo therapy device 110 having analternate pressure gauge 112 and a pressure relief tube 14. Cryo therapydevice 110 is substantially similar to cryo therapy device 10 exceptthat pressure gauge 112 comprises a horizontal strain gauge or fuselink. A horizontal strain gauge is substantially similar to the straingauge detailed above except that it may be disposed at inner member 26in a differing pattern. The differing pattern may be capable ofquantifying a different distribution of pressure within inner member 26.It can be appreciated that any number of differing shapes or patternsmay be used for pressure gauge 112 without departing from the spirit ofthe invention.

[0034] Similar to what is disclosed above cryo therapy device 110 mayfurther include pressure relief tube 14. Further, device 110 may includefuse link 52 and/or relief cutter 56. Fuse link 52 and/or relief cutter56 may be used in conjunction with pressure gauge 112 or with otherobjects or configurations described above.

[0035] Numerous advantages of the invention covered by this documenthave been set forth in the foregoing description. It will be understood,however, that this disclosure is, in many respects, only illustrative.Changes may be made in details, particularly in matters of shape, size,and arrangement of steps without exceeding the scope of the invention.The invention's scope is, of course, defined in the language in whichthe appended claims are expressed.

What is claimed is:
 1. A cryo therapy device, comprising: an elongateshaft having a proximal end and a distal end; a cooling member disposedat the distal end; wherein the cooling member includes an outer memberand an inner member; an inflation tube disposed within the shaft; adrain tube disposed within the shaft; and a pressure measurement deviceto the inner member.
 2. The cryo therapy device in accordance with claim1, wherein the pressure measurement device is directly couple to theinner member.
 3. The cryo therapy device in accordance with claim 1,further comprising a manifold disposed at the proximal end of theelongate shaft.
 4. The cryo therapy device in accordance with claim 3,wherein the pressure gauge is coupled to the manifold by a connector. 5.The cryo therapy device in accordance with claim 1, wherein the pressuregauge comprises a strain gauge.
 6. The cryo therapy device in accordancewith claim 1, wherein the pressure gauge includes a fuse link.
 7. Thecryo therapy device in accordance with claim 1, wherein the pressuregauge includes an optical transducer and a fiber optic output.
 8. Thecryo therapy device in accordance with claim 1, wherein the inner memberfurther comprises an outer surface and an inner surface.
 9. The cryotherapy device in accordance with claim 8, wherein the pressuremeasurement device is disposed on the inner surface.
 10. The cryotherapy device in accordance with claim 8, wherein the pressuremeasurement device is disposed on the outer surface.
 11. The cryotherapy device in accordance with claim 8, further comprising a reliefcutter coupled to the inner surface of the inner member.
 12. The cryotherapy device in accordance with claim 11, wherein the energy source isa radio-frequency energy source.
 13. The cryo therapy device inaccordance with claim 11, wherein the energy source is a laser energysource connected to the relief valve by fiber optic cable.
 14. The cryotherapy device in accordance with claim 11, wherein the energy source isan ultrasonic energy source mechanical coupled to relief valve.
 15. Thecryo therapy device in accordance with claim 1, further comprising apressure release tube having a proximal end, a distal end, and a lumenextending therethrough.
 16. The cryo therapy device in accordance withclaim 15, wherein the pressure release tube is in fluid communicationwith the inner member.
 17. The cryo therapy device in accordance withclaim 16, wherein the pressure release tube further comprises aremovable valve disposed at the proximal end thereof.
 18. The cryotherapy device in accordance with claim 15, wherein the pressure releasetube further comprises a pressure-sensitive valve disposed at the distalend thereof.
 19. The cryo therapy device in accordance with claim 15,further comprising a fuse link coupled to the pressure release tube. 20.The cryo therapy device in accordance with claim 19, wherein the fuselink is disposed over an opening within the pressure relief tube andwherein the fuse link is coupled to the pressure gauge.
 21. A cryotherapy device, comprising: an elongate shaft having a proximal end anda distal end; a manifold disposed at the proximal end; a cooling memberdisposed at the distal end; wherein the cooling member includes an innermember and an outer member; a pressure gauge coupled to the manifold bya connector; an inflation tube disposed within the shaft; a drain tubedisposed within the shaft; and a pressure release tube in fluidcommunication with the inner member.
 22. The cryo therapy device inaccordance with claim 21, wherein the pressure gauge includes a straingauge.
 23. The cryo therapy device in accordance with claim 21, whereinthe pressure gauge includes a fuse link.
 24. The cryo therapy device inaccordance with claim 21, wherein the inner member further comprises anouter surface and an inner surface.
 25. The cryo therapy device inaccordance with claim 24, wherein the pressure gauge is coupled to theinner surface.
 26. The cryo therapy device in accordance with claim 24,wherein the pressure gauge is coupled to the outer surface.
 27. The cryotherapy device in accordance with claim 21, wherein the pressure releasetube includes a proximal end, a distal end, and a lumen extendingtherethrough.
 28. The cryo therapy device in accordance with claim 27,wherein the pressure release tube further comprises a removable valvedisposed at the proximal end thereof.
 29. The cryo therapy device inaccordance with claim 27, wherein the pressure release tube furthercomprises a pressure-sensitive valve disposed at the distal end thereof.30. The cryo therapy device in accordance with claim 27, furthercomprising a fuse link coupled to the pressure release tube, wherein thefuse link is disposed over an opening within the pressure relief tubeand wherein the fuse link is coupled to the pressure gauge.
 31. A methodof performing cryoplasty, comprising the steps of: providing a cryotherapy device including an elongate shaft having a proximal end and adistal end, a manifold disposed at the proximal end, a cooling memberdisposed at the distal end, wherein the cooling member includes an outermember and an inner member, and a measuring device coupled to the innermember and coupled to the manifold by a connector such that pressurewithin the inner member may be quantified by the manifold; advancing thecryo therapy device to an area of interest; inflating the inner memberof the cooling member with a coolant to a pressure; quantifying thepressure with the pressure gauge; and cooling the area of interest withthe cooling member.
 32. The method in accordance with claim 31, whereinthe pressure gauge comprises a strain gauge and wherein the step ofquantifying the pressure with the pressure gauge includes quantifyingstrain.
 33. The method in accordance with claim 31, wherein the innermember further comprises an outer surface and an inner surface.
 34. Themethod in accordance with claim 33, wherein the pressure gauge iscoupled to the inner surface and wherein the step of quantifying thepressure with the pressure gauge includes quantifying pressure at theinner surface.
 35. The method in accordance with claim 33, wherein thepressure gauge is coupled to the outer surface and wherein the step ofquantifying the pressure with the pressure gauge includes quantifyingpressure at the outer surface.
 36. The method in accordance with claim31, further comprising a pressure release tube having a proximal end, adistal end, and a lumen extending therethrough.
 37. The method inaccordance with claim 36, wherein the pressure release tube furthercomprises a removable valve disposed at the proximal end thereof andfurther comprising the step of removing the removable valve from thepressure release tube in order to reduce pressure within the innermember.
 38. The method in accordance with claim 36, wherein the pressurerelease tube further comprises a pressure-sensitive valve disposed atthe distal end thereof and further comprising the step of reducingpressure within the inner member.